ISO/TR 23583

• Status: Not Published
• ICS: 27.010 - Energy and heat transfer engineering in general
• ICS: 77.060 - Corrosion of metals
• Technical Committee: ISO/TC 156 - Corrosion of metals and alloys
• Drafting Committee: ISO/TC 156/WG 9 - Corrosion testing of materials for power generation
• Current Stage: 6000 - International Standard under publication
• Start Date: 08-Jul-2026
• Completion Date: 29-Aug-2026

Overview

ISO/TR 23583: Sulfur Corrosion Test Method of Copper Winding in Electric Field for Power Equipment provides a standard framework for assessing the sulfur corrosion resistance of copper windings in power equipment. Developed by ISO Technical Committee 156, this technical report targets both newly installed and in-service electrical power equipment, focusing on simulating actual operating conditions to ensure more accurate and relevant test results. Sulfur corrosion is a critical reliability concern as it can contribute to copper degradation, reduce efficiency, and cause unexpected failures in transformers and other power devices.

This standard introduces a holistic test method that considers real-world scenarios, including electric field effects, oil quality, and the interaction between copper windings and insulating paper. By improving diagnostic practices and maintenance planning, ISO/TR 23583 aims to enhance the safety, longevity, and performance of electrical power grids.

Key Topics

• Simulated Operating Conditions: The method replicates real electric field stresses and environmental exposures encountered in actual power equipment to assess sulfur corrosion risks more accurately.
• Specimen Preparation: Involves creating ‘pig-tail’ models of copper windings wrapped with insulating paper, reflecting typical transformer construction.
• Testing in Insulating Oil: The copper winding specimens are immersed in transformer-grade insulating oil (e.g., conforming to IEC 60296), sometimes with added dibenzyl disulfide (DBDS), to simulate the presence of corrosive sulfur.
• Controlled Corrosion Acceleration: The test applies specific temperatures and electric field strengths to speed up corrosion processes, typically running for 3 days or more at set conditions.
• Qualitative and Quantitative Evaluation: Corrosion is assessed by:
  • Visual inspection of the winding surface for corrosion morphology.
  • Measuring copper ion content in the oil using methods such as inductively coupled plasma atomic emission spectroscopy (ICP-AES).
• Result Classification: The copper’s corrosion resistance is graded into defined levels based on copper content in the oil, supporting clear maintenance and quality decisions.

Applications

• Power Transformers: Directly relevant for manufacturers and operators seeking to ensure long-term reliability and efficiency of transformer units by minimizing sulfur-induced copper degradation.
• Quality Assurance: Utilities and third-party labs can use this method to assess and certify that copper windings and insulating oils meet strict sulfur corrosion resistance standards before installation.
• Failure Analysis: Supports root-cause investigations when power equipment experiences premature aging or breakdown, helping to identify sulfur corrosion as a contributing factor.
• Research and Development: Enables R&D teams to compare the performance of alternative materials, insulation systems, or oils under controlled but realistic conditions.
• Regulatory Compliance: Assists in conforming to international best practices and harmonizes testing requirements across industries and geographies.

Related Standards

To ensure comprehensive sulfur corrosion evaluation and align with established international practices, consider the following standards referenced or related to ISO/TR 23583:

• ASTM D 1275A/B: Standards for detecting corrosive sulfur in electrical insulating oils.
• IEC 62535: Methods for identifying potentially corrosive sulfur in used and unused insulating oils.
• GB/T 25961: Chinese national standard on sulfur corrosion test methods for electrical insulating oils.
• ASTM D 130: Assessment of copper strip corrosion in petroleum products.
• ISO 6251: Testing of copper corrosiveness of liquefied petroleum gases.
• IEC 60296: Technical requirements for mineral insulating oils used in electrical equipment.
• GB/T 6451: Specification for oil-immersed power transformer copper windings and materials.

Adopting ISO/TR 23583 alongside these related standards helps the power industry better manage sulfur corrosion risks, safeguard assets, and ensure a resilient electricity supply.

FINAL DRAFT
Technical
Report
ISO/DTR 23583
ISO/TC 156
Sulfur corrosion test method of
Secretariat: SAC
copper winding in electric field for
Voting begins on:
power equipment
2026-05-12
Voting terminates on:
2026-07-07
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/DTR 23583:2026(en) © ISO 2026

FINAL DRAFT
ISO/DTR 23583:2026(en)
Technical
Report
ISO/DTR 23583
ISO/TC 156
Sulfur corrosion test method of
Secretariat: SAC
copper winding in electric field for
Voting begins on:
power equipment
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DTR 23583:2026(en) © ISO 2026

ii
ISO/DTR 23583:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General regulation . 1
5 Specimen preparation . . 2
5.1 Copper winding .2
5.2 Insulating oil .2
5.3 Insulating paper .2
5.4 Dibenzyl disulfide .2
6 Instruments and equipment . 2
6.1 Thermostatic oil tank .2
6.2 Vacuum drying immersion oil tank .3
6.3 Electric heating experimental tank .3
6.4 DC/AC power supply .4
6.5 Plasma coupled atomic emission spectrometer.4
7 Preparation of test . 4
7.1 Establishing a pig-tail model .4
7.2 Drying treatment.4
7.3 Immersion oil .4
8 Test procedures . 5
8.1 Heating.5
8.2 Remove the sample after cooling .6
9 Evaluation of oil sulfur corrosion resistance performance . 6
9.1 Qualitative evaluation .6
9.2 Quantitative evaluation .6
9.3 Quantitative evaluation .6
Bibliography . 7

iii
ISO/DTR 23583:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO/DTR 23583:2026(en)
Introduction
Many factors affect the sulfur corrosion of copper windings in power equipment in the power industry.
These include:
— temperature;
— corrosive sulfide concentration in oil;
— acid products derived from oil-paper insulation aging;
— moisture;
— the type of electric field (AC or DC electric field);
— electric field strength;
— the contact state between the copper winding and the insulating paper;
— the quality of the copper winding.
These have a significant influence on the occurrence of sulfur corrosion and the generation of corrosion
products. The current assessment methods of sulfur corrosion of copper windings do not sufficiently
consider these factors. Existing standards (e.g. ASTM D 1275A, ASTM D 1275B, IEC 62535, GB/T 25961) test
specifications or methods for testing whether the quality of insulating oil meets the requirements.
As for the corrosion of copper, the existing standards are test methods for the co
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ISO #####-#:####(X/DTR 23583:(en) Formatted: Font: 11 pt, Bold
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
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may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
between Latin and Asian text, Adjust space between
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
Asian text and numbers, Border: Top: (No border)
at the address below or ISO’s member body in the country of the requester.
Formatted: Left: 1.5 cm, Right: 1.5 cm, Bottom: 1 cm,
Header distance from edge: 1.27 cm, Footer distance
ISO copyright office
from edge: 0.5 cm
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Formatted: French (Switzerland)
EmailE-mail: [e-mail]
Formatted: French (Switzerland)
Website: www.iso.orgwww.iso.org
Formatted: French (Switzerland)
Published in Switzerland
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: Font: 11 pt
Formatted: FooterPageRomanNumber, Space After: 0
pt, Line spacing: single
ii © ISO #### 2026 – All rights reserved
ii
ISO/DTR 23583:(en)
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold, English (United Kingdom)
Formatted: Font: 11 pt, Bold
Contents
Formatted: HeaderCentered, Left, Space After: 0 pt,
Line spacing: single
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General regulation . 1
5 Specimen preparation . 2
5.1 Copper winding . 2
5.2 Insulating oil . 2
5.3 Insulating paper . 2
5.4 Dibenzyl disulfide . 2
6 Instruments and equipment . 2
6.1 Thermostatic oil tank . 2
6.2 Vacuum drying immersion oil tank . 3
6.3 Electric heating experimental tank . 3
6.4 DC/AC power supply . 4
6.5 Plasma coupled atomic emission spectrometer . 4
7 Preparation of test . 4
7.1 Establishing a pig-tail model . 4
7.2 Drying treatment . 4
7.3 Immersion oil . 5
8 Test procedures . 7
8.1 Heating . 7
8.2 Remove the sample after cooling . 7
9 Evaluation of oil sulfur corrosion resistance performance . 7
9.1 Qualitative evaluation . 7
9.2 Quantitative evaluation . 7
9.3 Quantitative evaluation . 7
Bibliography . 9

Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General regulation . 1
5 Specimen preparation . 2
Formatted: Font: 10 pt
5.1 Copper winding . 2
Formatted: Font: 10 pt
5.2 Insulating oil . 2
5.3 Insulating paper . 2 Formatted: FooterCentered, Left, Line spacing: single
5.4 Dibenzyl disulfide . 2
Formatted: Font: 11 pt
6 Instruments and equipment . 2
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6.1 Thermostatic oil tank . 2
After: 0 pt, Line spacing: single
© ISO TR 23583 2026 – All rights reserved
iii
ISO #####-#:####(X/DTR 23583:(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: HeaderCentered, Left, Space After: 0 pt,
6.2 Vacuum drying immersion oil tank. 2
Line spacing: single
6.3 Electric heating experimental tank . 2
6.4 DC/AC power supply. 3
6.5 Plasma coupled atomic emission spectrometer . 3
7 Preparation of test . 3
7.1 Establish a pig-tail model . 3
7.2 Drying treatment . 4
7.3 Immersion oil . 4
8 Test procedures . 5
8.1 Heating . 5
8.2 Remove the sample after cooling . 5
9 Evaluation of oil sulfur corrosion resistance performance . 5
9.1 Qualitative evaluation . 5
9.2 Quantitative evaluation . 5
9.3 Quantitative evaluation . 5
Bibliography . 错误！未定义书签。

Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: Font: 11 pt
Formatted: FooterPageRomanNumber, Space After: 0
pt, Line spacing: single
iv © ISO #### 2026 – All rights reserved
iv
ISO/DTR 23583:(en)
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold, English (United Kingdom)
Formatted: Font: 11 pt, Bold
Foreword
Formatted: HeaderCentered, Left, Space After: 0 pt,
Line spacing: single
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Formatted: Default Paragraph Font
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for identifying any or all such
patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
Formatted: Font: Not Italic
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html.
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: FooterCentered, Left, Line spacing: single
Formatted: Font: 11 pt
Formatted: FooterPageRomanNumber, Left, Space
After: 0 pt, Line spacing: single
© ISO TR 23583 2026 – All rights reserved
v
ISO #####-#:####(X/DTR 23583:(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: HeaderCentered, Left, Space After: 0 pt,
Introduction
Line spacing: single
Many factors affect the sulfur corrosion of copper windings in power equipment in the power industry. These
include:
— — temperature;
Formatted: List Continue 1
— — corrosive sulfide concentration in oil;
— — acid products derived from oil-paper insulation aging;
— — moisture;
— — the type of electric field (AC or DC electric field);
— — electric field strength;
— — the contact state between the copper winding and the insulating paper;
— — the quality of the copper winding.
These have a significant influence on the occurrence of sulfur corrosion and the generation of corrosion
products. Unfortunately, theThe current assessment methods of sulfur corrosion of copper windings do not
sufficiently consider these factors. Existing standards (e.g. ASTM D 1275A/B, ASTM D 1275B, IEC 62535, GB/T
Formatted: English (United Kingdom)
25961) test specifications or methods for testing whether the quality of insulating oil meets the requirements.
As for the corrosion of copper, the existing standards are test methods for the corrosion of copper metal in the
atmospheric environment, petroleum products, etc. Standards such as GB/T 38265.15, ASTM D 130 and ISO
6251specify6251 specify special testing or assessment methods for lubricants, oil and copper parts in
atmospheric environments (e.g. pipelines, tower parts and other structures), which does not fully apply to
power equipment.
Therefore, with reference to the existing standards for corrosive sulfur detection in insulating oil, this
document proposes a sulfur corrosion test method for copper winding in electric field for power equipment.
The method includes pre-treatment, model construction, the corrosion test method and corrosion level
judgments for copper windings.
This document contributes to controlling the quality of copper windings in electric power equipment,
reducing the failure of electric power equipment due to sulfur corrosion and prolonging the service life of
power equipment, which has great significance in improving the safe operation of power grids.
This document considers the effects of actual working conditions (e.g. electric field, the contact state between
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